This invention relates generally to carbon filters having replaceable filter beds, and more particularly to a machine and method for replenishing the carbon material in trays for such filter beds.
A type of filter for removal of radioactive iodine from atmospheric air in nuclear power plants is designated CS-8T by the American Association for Contamination Control (AACC) of Boston, Mass. Such filters include a filter tray having parallel spaced beds of adsorbent carbon which may be, for example, activated cocoanut shell base granular charcoal serving as a carbon dioxide adsorber. These trays must be periodically rejuvenated. It is typically done by removing all of the carbon and replacing it. The conventional procedure known to me for doing so is to mount the tray on a fixture which holds the tray so that the fill end of it faces up. A hopper is fastened to the fill end of the tray. Granular charcoal is dumped from a drum into the hopper and falls from the hopper into the filter tray to fill up the two beds. The fixture has a vibrator attached to it to shake the fixture with the tray therein in a vertical direction to compact the charcoal to the necessary density to meet the specifications for such trays.
This prior art procedure has some attendant problems. These include difficulty in obtaining the desired uniformity of density of charcoal in the filter beds, contamination of the filling charcoal due to environmental dirt or gases, difficulty in control of the charcoal being dumped into the hopper, resulting in contamination of the area around the filter filling station with the charcoal that spills contamination of spilled charcoal making it unusable, and contamination of the air with the charcoal fines that get into the air.